The present invention relates to an enclosed storage battery, and more particular to the bushing structure of the terminal unit of the storage battery.
In the enclosed storage battery, the input and output terminals have welded portions of poles penetrating from inside of the jar to the outside. It is important that the areas between the poles and penetration holes in the peripheral areas of poles be kept air-tight and closed.
A bushing structure of terminal unit of a conventional enclosed storage battery is shown in FIG. 10. In FIG. 10, a lid 102 is placed to cover the opening of a jar 101. A lead-alloy bushing 103 is buried in the lid 102. A pole 105 is inserted into a penetration hole 104 formed in the bushing, and this pole 105 is integrally welded to an L-shaped input and output terminal 106 placed on the top of the bushing 103. The leading end of the pole 105 penetrating through the penetration hole 104 of the bushing 103 is welded to the upper periphery of the bushing 103, and is further welded and integrated while filling a cavity 107 of the L-shaped input and output terminal 106 with fused lead.
On the other hand, as a modified example of terminal of a conventional enclosed storage battery, the following constitution is known (not shown). That is, the bushing 103 is not formed integrally to the lid 102 at the lower end of the penetration hole 104, but generally the lower end of the bushing 103 is projecting from the inner side of the lid 102 to the inner side direction of the penetration hole 104. Accordingly, when inserting the pole 105 into the penetration hole 104 from the inner side of the jar 101, the leading end of the pole 105 hits against the lower end of the bushing 103, and the pole 105 cannot be smoothly inserted into the penetration hole 104.
In such connection method of bushing 103 and pole 105, since the upper part of the bushing 103 and the top of the pole 105 are on a same plane, and only the leading end periphery of the pole 105 is welded to the bushing 103, the welding region is small, and the strength at the junction was insufficient.
Moreover, the alloy in the weld zone is a non-uniform mixed alloy, and corrosion initiates from the grain boundary, and, as a result, the electrolyte oozes out. Besides, since the mixed alloy of the weld zone is similar to the material of the pole, and it is soft and insufficient in strength.
To compensate for shortage in strength, it is proposed to reinforce by placing the L-shaped input and output terminal 106 on the bushing 103, and filling the cavity 107 formed in the input and output terminal 106 with a fused lead by melting an additional lead. This additional lead is made of same alloy material as the lead alloy for composing the terminal, and hence the material strength is sufficiently assured, but such manufacturing process of storage battery is may be complicated and may require many steps.
The enclosed storage battery of the invention comprises:
(a) a jar having an opening,
(b) plate group and electrolyte placed in the jar,
(c) a lid placed in the opening having
(1) a conductive bushing having a penetration hole penetrating from inside to outside of the jar, being formed of a first fusible material, and
(2) a conductive terminal electrically connected to the bushing,
(d) a conductive pole electrically connected to the plate group, inserted and set in the penetration hole, and formed of a second fusible material, and
(e) at least one fused matter joining the pole and the bushing selected from
(i) a first fused matter formed by melting the bushing, and
(ii) a second fused matter formed by melting the pole.
The manufacturing method of enclosed storage battery of the invention comprises:
(a) a step of placing a plate group in a jar having an opening,
(b) a step of injecting electrolyte into the jar,
(c) a step of connecting a pole to the plate group,
(d) a step of placing a terminal and a lid having a bushing electrically conducting with the terminal so as to cover the opening,
(e) a step of inserting the pole into a penetration hole formed in the bushing, from inside of the jar, and
(f) a step of integrating the pole and the bushing by at least one step selected from
(1) a step of melting part of the pole, and joining the pole and the bushing by a second fused matter formed by its melting, and
(2) a step of melting the upper part of the penetration hole of the bushing, and joining the pole and the bushing by a first fused matter formed by its melting.
Preferably, the first fusible material of the bushing is formed of at least one material of lead and lead alloy.
Preferably, the second fusible material of the pole is formed of at least one material of lead and lead alloy.
Preferably, the second fused matter formed by melting the leading end of the pole is joining the pole and the bushing.
Preferably, the first fused matter formed by melting the bushing is joining the pole and the bushing.
Preferably, the lid is formed of a material including resin.
Preferably, the peripheral portion of the top of the pole has at least one surface of round surface and curved surface.
Preferably, the lower side of the lid positioned at the lower end of the penetration hole has a taper form.
Preferably, a terminal cover is further placed in the lid so as to cover the bushing.
In this constitution, the adhesion strength of the pole and bushing is extremely enhanced. Further, the tightness is improved.
Moreover, corrosion of the junction of the pole and bushing is prevented, and leak of electrolyte is prevented.
Thus, the enclosed storage battery with an excellent reliability having the above properties is obtained.
In a simple manufacturing process, the enclosed storage battery having an excellent adhesion strength of pole and bushing is manufactured.